For best results, have another person assist you, use a fabric tape measure, and be sure to wear minimal clothing.

Chest:

Wrap the tape around the fullest area of your chest. The tape should be flat but not too snug.

Natural Waist:

Your natural waist is at the smallest point between your bottom ribs and hip bones (higher than where most people wear their pants). Measure around your natural waist making sure the tape in flat but not too snug.

Hip:

Measure around the widest part of your hips (including the buttocks), making sure the tape is horizontal and not angled.